Well it depends of their levels. If others are 30 levels lower than strongest player, weaker players will not recieve exp.
And set Party Range to higher number
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In other.PROPERTIES find:
# PARTY XP DISTRIBUTION
# Set the first option here to one of the (auto, percentage, level, none).
# With "auto method" member is cut from Exp/SP distribution when his share is lower
# then party bonus acquired for him (30% for 2 member party)
# In that case he will not receive any Exp/SP from party and is not counted for party bonus
# The second option takes effect when "percentage" method is choosen. Don't use high values for this!
# The third option takes effect when "level" method is choosen. Don't use low values for this!
# If you don't want to have a cutoff point for party members' XP distribution,
# then just set the first option to "none". Defaults are: percentage , 3.0 , 30 ; respectively.
PartyXpCutoffMethod = auto
PartyXpCutoffPercent = 3.0
PartyXpCutoffLevel = 30
PartyRange = 2500
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Edit PartyXpCutoffLevel =*** and PartyRange =***
(*** is your number)